This article describes a nurse manager's participation in a research project evaluating Parse's theory of nursing in an acute care setting. The project favourably influenced quality of care and nurse satisfaction on a medical unit which led to the adoption of Parse's theory as the permanent theoretical guide. The manager describes the decision to test Parse's theory, the process of change and the differences for staff nurses and patients. It was discovered that theory based practice offered new direction and purpose for nursing practice. From the perspective of a manager Parse's theory offered the opportunity to develop a more cohesive and humanistic nursing unit and to challenge staff nurses to think seriously about what their "practice" of nursing really means.